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論文

Gradient residual strain determination of surface impacted railway S38C axles by neutron Bragg-edge transmission imaging

Hu, F. F.*; Qin, T. Y.*; Ao, N.*; Su, Y. H.; Zhou, L.*; 徐 平光; Parker, J. D.*; 篠原 武尚; Chen, J.*; Wu, S. C.*

Engineering Fracture Mechanics, 306, p.110267_1 - 110267_18, 2024/08

Non-destructive and quantitative mapping of gradient residual strain distribution in surface-hardened railway S38C axles could provide a positive reference for determining service lifetime and maintenance strategy. To tackle this concern, time-of-flight neutron Bragg-edge transmission imaging was employed by real axle samples with and without impacted crater. A novel and simple procedure to formulate the residual strain field was also developed in this work, with the transmission batch code in Appendix A. By mapping the global two- dimensional residual strains, it can be verified that the residual strains into the axle are uniformly distributed in the hoop direction. Subsequently, it was revealed that the axial and hoop residual strains, respectively in the cylinder and the long strip samples prepared from a real S38C hollow axle, indicated a gradient evolution distribution with a depth of $$sim$$ 8 mm, covering a range of -5500 $$sim$$ 1000 $$mu$$$$varepsilon$$ for axial strains and -6500 $$sim$$ 1000 $$mu$$$$varepsilon$$ for hoop strains. More importantly, the maximum compressive lattice strain of the cylinder sample was increased by 15.61%, and 22.35% at the impacting speeds of 100, and 125 m/s, respectively; and that of the long strip sample increased by 29.17%, and 43.70%, respectively. It can thus be concluded that lattice strains have redistributed around the impact crater, demonstrating the local alteration of the residual strain field. These new findings suggest the localized variation in residual strains should be taken into account while evaluating the service damage evolution of railway axles, especially those affected by high-speed impacts during operation.

論文

Gradient residual stress and fatigue life prediction of induction hardened carbon steel S38C axles; Experiment and simulation

Qin, T. Y.*; Hu, F. F.*; 徐 平光; Zhang, H.*; Zhou, L.*; Ao, N.*; Su, Y. H.; 菖蒲 敬久; Wu, S. C.*

International Journal of Fatigue, 185, p.108336_1 - 108336_13, 2024/08

Gradient distribution of triaxial residual stresses to a depth of several millimeters is retained in middle carbon steel S38C axles after high-frequency induction hardening, which has become a critical concern for fatigue structural integrity. To address this, the axial, hoop, and radial gradient residual strains inside the axles were measured for the first time by advanced neutron diffraction. The SIGINI Fortran subroutine was then adopted to reconstruct the global initial residual stress field from the measured data. Experimental and simulation results show that residual stresses of about -520 MPa (axial), -710 MPa (hoop), and -40 MPa (radial) residual stress were retained below the axle surface. Subsequently, the fatigue crack propagation behavior of S38C axles was numerically investigated in the framework of fracture mechanics. The calculated results clearly show that the compressive residual stresses at a depth of 0?3 mm from the axle surface lead to a low crack growth driving force, and that fatigue cracks do not propagate as long as the crack depth is less than 3.7 mm for hollow S38C axles. These results further indicate that the maximum defect size allowed in routine inspections is acceptable from a safety and economic point of view. Accurate measurement and characterization of the global gradient residual stress field through experiments and simulations can provide an important reference for optimizing the mileage intervals of nondestructive testing (NDT) of surface defects in these surface-strengthened railway axles.

論文

Gradient residual strain measurement procedure in surface impacted railway steel axles by using neutron scattering

Zhou, L.*; Zhang, H.*; Qin, T. Y.*; Hu, F. F.*; 徐 平光; Ao, N.*; Su, Y. H.; He, L. H.*; Li, X. H.*; Zhang, J. R.*; et al.

Metallurgical and Materials Transactions A, 55(7), p.2175 - 2185, 2024/07

 被引用回数:0 パーセンタイル:0.02(Materials Science, Multidisciplinary)

High-speed railway S38C axles undergo surface induction hardening for durability, but are susceptible to fatigue cracks from foreign object impact. The neutron diffraction method was employed to measure the residual strain in S38C axles, obtaining microscopic lattice distortion data, for the gradient layer at a depth of 8 mm under the surface. The results showed that after induction-hardening, the microscopic lattice distortion had a gradient distribution, decreasing with the distance from the surface. However, in the case of impacting speed of 600 km/m, the average microscopic lattice distortion increased with the distance from the surface, reaching a maximum augmentation of 55 pct. These findings indicate a strong experimental basis, and improve our understanding of the relationship between macroscopic residual stress and decision-making, in regard to operation and maintenance.

論文

Recrystallization of bulk nanostructured magnesium alloy AZ31 after severe plastic deformation; An in situ diffraction study

Liss, K.-D.*; Han, J.-K.*; Blankenburg, M.*; Lienert, U.*; Harjo, S.; 川崎 卓郎; 徐 平光; 行武 栄太郎*; Kawasaki, M.*

Journal of Materials Science, 59(14), p.5831 - 5853, 2024/04

 被引用回数:0 パーセンタイル:0.00(Materials Science, Multidisciplinary)

The magnesium alloy AZ31, which has undergone high-pressure torsion processing, was subjected to in situ annealing micro-beam synchrotron high-energy X-ray diffraction and compared to the as-received rolled sheet material that was investigated through in situ neutron diffraction. While the latter only exhibits thermal expansion and minor recovery, the nanostructured specimen displays a complex evolution, including recovery, strong recrystallization, phase transformations, and various regimes of grain growth. Nanometer-scale grain sizes, determined using Williamson-Hall analysis, exhibit seamless growth, aligning with the transition to larger grains, as assessed through the occupancy of single grain reflections on the diffraction rings. The study uncovers strain anomalies resulting from thermal expansion, segregation of Al atoms, and the kinetics of vacancy creation and annihilation. Notably, a substantial number of excess vacancies were generated through high-pressure torsion, and maintained for driving the recrystallization and forming highly activated volumes for diffusion and phase precipitation during heating. The unsystematic scatter observed in the Williamson-Hall plot indicates high dislocation densities following severe plastic deformation, which significantly decreases during recrystallization. Subsequently, dislocations reappear during grain growth, likely in response to torque gradients in larger grains. It is worth noting that the characteristics of unsystematic scatter differ for dislocations created at high and low temperatures, underscoring the strong temperature dependence of slip system activation.

論文

Abnormal grain growth; A Spontaneous activation of competing grain rotation

Liss, K.-D.*; 徐 平光; 城 鮎美*; Zhang, S. Y.*; 行武 栄太郎*; 菖蒲 敬久; 秋田 貢一*

Advanced Engineering Materials, 26(4), p.202300470_1 - 202300470_9, 2024/02

In polycrystals, grains with certain orientations grow at high temperatures at the expense of grains with other unfavorable orientations. Grain growth involves a variety of situations and mechanisms that make experimental study, modeling, and understanding extremely complex. Normal grain growth occurs in a self-similar manner, with curved grain boundaries serving as the driving force and a parabolic growth law that scales up the grain size by the square root of time. More complex growth forms include boundary pinning of precipitates and other boundaries, topological transitions that alter driving forces, grain coalescence and anomalous grain growth, but these are considered "erratic" and their initiation is an open question in modern research, without a simple experimental approach on how they should be studied. Here, we show that grain rotation upon coalescence is spontaneously activated between one grain and a favorable neighbor, through the necessary diffusive mass transport at further boundaries of the same grain leading to their activation and a competitive "erratic" reorientation in a zigzag way, while other grains in the matrix remain stable. After two grains have eventually coalesced, their surrounding boundaries are still activated leading to further rotation and growth, filling the missing puzzle stone in thermodynamic theory between normal and abnormal growth, the latter stating that abnormal growth only takes place when the size of the growing grain is already large. Prerequisites and postulates of abnormal grain growth are based on advantageous texture, grain boundary mobility, enhanced diffusion kinetics and coalescence, which can be well explained by our observations. Moreover, our observations have been enabled through a novel experimental approach using the white-beam X-ray Laue diffraction method in bulk transmission mode on a polycrystalline.

論文

System of radiological protection; Towards a consistent framework on earth and in space

R$"u$hm, W.*; 伴 信彦*; Chen, J.*; Li, C.*; Dobynde, M.*; Durante, M.*; El-Jaby, S.*; 込山 立人*; 小笹 晃太郎*; 佐藤 達彦; et al.

Journal of Medical Physics - Zeitschrift f$"u$r medizinische Physik -, 34(1), p.4 - 13, 2024/02

 被引用回数:0 パーセンタイル:0.12

国際放射線防護委員会(ICRP)は、過去90年間に渡って世界各国や国際的な放射線防護の枠組み作りに貢献してきた。2019年、ICRPは宇宙飛行士の放射線防護に関わる様々な問題に対応したタスクグループ(TG115)を立ち上げ、地上の放射線防護体系と宇宙の放射線防護体系との共通の枠組み作りに取り組んでいる。本論文では、現時点でICRPが定めている宇宙放射線防護体系についてとりまとめて報告する。

論文

Principal preferred orientation evaluation of steel materials using time-of-flight neutron diffraction

徐 平光; Zhang, S.-Y.*; Harjo, S.; Vogel, S. C.*; 友田 陽*

Quantum Beam Science (Internet), 8(1), p.7_1 - 7_13, 2024/01

Comprehensive information about the ${it in situ}$ microstructure and crystal structure evolution during the preparation/production processes of various materials is in great demand in order to precisely control the microstructure morphology and the preferred orientation characteristics for the excellent strength-ductility-toughness balance of advanced engineering materials. ${it In situ}$ isothermal annealing experiments of cold rolled 17Ni-0.2C (mass %) martensitic steel sheets were carried out by using the TAKUMI and ENGIN-X time-of-flight neutron diffractometers, respectively. The inverse pole figures based on full-profile refinement were extracted to roughly evaluate the preferred orientation features along three principal sample directions of investigated steel sheets using the General Structure Analysis System (GSAS) software with built-in generalized spherical harmonic functions. The consistent rolling direction (RD) inverse pole figures from TAKUMI and ENGIN-X have confirmed that the time-of-flight neutron diffraction has high repeatability and statistical reliability, revealing that the principal preferred orientation evaluation of steel materials is available through 90$$^{circ}$$ TD $$rightarrow$$ ND (transverse direction $$rightarrow$$ normal direction) rotation of the investigated specimen on the sample stage during two neutron diffraction experiments. Moreover, these RD, TD and ND inverse pole figures before and after in situ experiments were compared with the corresponding inverse pole figures recalculated respectively from the MUSASI-L complete pole figure measurement and the HIPPO in situ microstructure evaluation. The similar orientation distribution characteristics suggested that the principal preferred orientation evaluation method can be applied to in situ microstructure evolution of bulk orthorhombic materials and spatially resolved principal preferred orientation mappings of large engineering structure parts.

論文

Electromagnetic moments of the antimony isotopes $$^{112-133}$$Sb

Lechner, S.*; 宮城 宇志*; Xu, Z. Y.*; Bissell, M. L.*; Blaum, K.*; Cheal, B.*; Devlin, C. S.*; Garcia Ruiz, R. F.*; Ginges, J. S. M.*; Heylen, H.*; et al.

Physics Letters B, 847, p.138278_1 - 138278_9, 2023/12

 被引用回数:0 パーセンタイル:0.02(Astronomy & Astrophysics)

不安定核を含むアンチモン同位体$$^{112-133}$$Sbの磁気モーメントと電気的四重極モーメントをレーザー分光を用いて測定した。現象論的な相互作用と有効演算子を用いた殻模型計算によって測定値をよく再現することができた。第一原理に基づいたVS-IMSRG法による殻模型計算では、磁気モーメントは現象論的な有効演算子を用いればよく実験値を再現するものの、電気的四重極モーメントについては有効電荷を用いても現象論的な相互作用を用いた計算ほどには実験値を再現することができなかった。

論文

Level structures of $$^{56,58}$$Ca cast doubt on a doubly magic $$^{60}$$Ca

Chen, S.*; Browne, F.*; Doornenbal, P.*; Lee, J.*; Obertelli, A.*; 角田 佑介*; 大塚 孝治*; 茶園 亮樹*; Hagen, G.*; Holt, J. D.*; et al.

Physics Letters B, 843, p.138025_1 - 138025_7, 2023/08

 被引用回数:1 パーセンタイル:59.27(Astronomy & Astrophysics)

$$^{57,59}$$Scからの1陽子ノックアウト反応を用いて、$$^{56}$$Caと$$^{58}$$Caのガンマ崩壊を観測した。$$^{56}$$Caでは1456(12)keVの$$gamma$$線遷移が、$$^{58}$$Caでは1115(34)keVの遷移が観測された。どちらの遷移も暫定的に$$2^{+}_{1} rightarrow 0^{+}_{gs}$$と割り当てられた。有効核子間相互作用をわずかに修正した広い模型空間での殻模型計算では、$$2^{+}_{1}$$準位エネルギー、2中性子分離エネルギー、反応断面積が実験とよく一致し、N=34閉殻の上に新しい殻が形成されていることを裏付けた。その構成要素である$$0_{f5/2}$$$$0_{g9/2}$$軌道はほぼ縮退しており、これは$$^{60}$$Caが二重魔法核である可能性を排除し、Ca同位体のドリップラインを$$^{70}$$Caあるいはそれ以上にまで広げる可能性がある。

論文

Corrosion fatigue crack growth behavior of a structurally gradient steel for high-speed railway axles

Ao, N.*; Zhang, H.*; Xu, H. H.*; Wu, S. C.*; Liu, D.*; 徐 平光; Su, Y. H.; Kang, Q. H.*; Kang, G. Z.*

Engineering Fracture Mechanics, 281, p.109166_1 - 109166_14, 2023/03

 被引用回数:5 パーセンタイル:89.51(Mechanics)

Considering the complex service environments that high-speed railway axles are subjected to, the fatigue crack growth (FCG) behavior of a structurally gradient axle steel with different pre-crack depths both in air and corrosive medium was investigated at a frequency of 5 Hz. The results indicated that in the high $$Delta$$$$K$$ region, FCG rate was dramatically accelerated by corrosion, but the gap narrows as $$Delta$$$$K$$ decreased. The accelerated corrosion FCG rate was a comprehensive result of the acceleration effect of the anodic dissolution, hydrogen-enhanced localized plasticity and the retardation effect of corrosion-induced crack-tip blunting. Despite the fact that the corrosion resistance gradually decreased as the pre-crack depth increased, the FCG rate in the corrosive medium gradually decreased. This was because fatigue loading played a more important role than corrosion in accelerating the corrosion FCG rate.

論文

Fatigue crack non-propagation behavior of a gradient steel structure from induction hardened railway axles

Zhang, H.*; Wu, S. C.*; Ao, N.*; Zhang, J. W.*; Li, H.*; Zhou, L.*; 徐 平光; Su, Y. H.

International Journal of Fatigue, 166, p.107296_1 - 107296_11, 2023/01

 被引用回数:4 パーセンタイル:56.68(Engineering, Mechanical)

Abnormal damages in railway axles can lead to a significant hazard to running safety and reliability. To this end, a surface treatment was selected to effectively inhibit fatigue crack initiation and growth. In this study, a single edge notch bending fatigue test campaign with artificial notches was conducted to elucidate the fatigue crack non-propagation behavior in railway S38C axles subjected to an induction hardening process. The fatigue cracking behavior in the gradient structure was revealed by optical microscopy, electron backscatter diffraction, and fractography. The microhardness distribution was measured using a Vickers tester. The obtained results show that the microhardness of the strengthening layer is nearly triple that of the matrix. Owing to the gradient microstructures and hardness, as well as compressive residual stress, the fatigue long crack propagates faster once it passes through the hardened zone (approximately 2.0 mm in the radial depth). Thereafter, local retarding (including deflection, branching, and blunting) of the long crack occurs because of the relatively coarse ferrite and pearlite in the transition region and matrix. Totally, this fatigue cracking resistance is reasonably believed to be due to the gradient microstructure and residual stress. These findings help to tailor a suitable detection strategy for maximum defects or cracks in railway axles.

論文

Heat-induced structural changes in magnesium alloys AZ91 and AZ31 investigated by in situ synchrotron high-energy X-ray diffraction

Liu, X. J.*; 徐 平光; 城 鮎美*; Zhang, S. Y.*; 菖蒲 敬久; 行武 栄太郎*; 秋田 貢一*; Zolotoyabko, E.*; Liss, K.-D.*

Journal of Materials Science, 57(46), p.21446 - 21459, 2022/12

 被引用回数:3 パーセンタイル:36.97(Materials Science, Multidisciplinary)

In situ time/temperature-resolved synchrotron high-energy X-ray diffraction is applied to study heat-mediated structural changes and phase transformations in rolled sheets of AZ91 and AZ31 magnesium alloys. Azimuthal diffraction intensities along the Debye-Scherrer rings (AT-plots) are used to obtain information on grain recovery and recrystallization temperatures as well as temperature-assisted grain rotations. The azimuthally integrated diffraction intensities, plotted as functions of the scattering vector (QT-plots), provide vital data on the temperature-dependent lattice parameters of the Mg/Al matrix and intermetallic precipitates, as well as on the evolution of the precipitates' volume fraction. It was found that in AZ31, the main precipitates are of the AlMn type, which is rather stable in the investigated temperature range (up to 773 K). In contrast, in AZ91, the major intermetallic precipitates, Al$$_{12}$$Mg$$_{17}$$, undergo complete dissolution above 600 K. It is caused by the enhanced diffusion of Al into the Mg/Al matrix, which according to the Al-Mg phase diagram, can adopt more Al at elevated temperatures. This diffusion is revealed by the proportional diminishing of the matrix lattice parameter (chemical strain), allowing us to quantify the Al content in the matrix. Fast temperature-dependent manipulation with intermetallic content in the Mg/Al alloy can, in principle, be used for controlling its mechanical properties.

論文

The $$^{59}$$Fe(n,$$gamma$$)$$^{60}$$Fe cross section from the surrogate ratio method and its effect on the $$^{60}$$Fe nucleosynthesis

Yan, S. Q.*; Li, X. Y.*; 西尾 勝久; Lugaro, M.*; Li, Z. H.*; 牧井 宏之; Pignatari, M.*; Wang, Y. B.*; Orlandi, R.; 廣瀬 健太郎; et al.

Astrophysical Journal, 919(2), p.84_1 - 84_7, 2021/10

 被引用回数:1 パーセンタイル:8.24(Astronomy & Astrophysics)

The long-lived $$^{60}$$Fe (with a half-life of 2.62 Myr) is a crucial diagnostic of active nucleosynthesis in the Milky Way galaxy and in supernovae near the solar system. The neutron-capture reaction $$^{59}$$Fe(n,$$gamma$$)$$^{60}$$Fe on $$^{59}$$Fe (half-life=44.5 days) is the key reaction for the production of $$^{60}$$Fe in massive stars. This reaction cross section has been previously constrained by the Coulomb dissociation experiment, which offered partial constraint on the E1 $$gamma$$-ray strength function but a negligible constraint on the M1 and E2 components. In this work, for the first time, we use the surrogate ratio method to experimentally determine the $$^{59}$$Fe(n,$$gamma$$)$$^{60}$$Fe cross sections in which all the components are included. We derived a Maxwellian-averaged cross section of 27.5$$pm$$3.5 mb at $$kT$$ = 30 keV and 13.4$$pm$$1.7 mb at $$kT$$ = 90 keV, roughly 10%-20% higher than previous estimates. We analyzed the impact of our new reaction rates in nucleosynthesis models of massive stars and found that uncertainties in the production of $$^{60}$$Fe from the $$^{59}$$Fe(n,$$gamma$$)$$^{60}$$Fe rate are at most 25$$%$$. We conclude that stellar physics uncertainties now play a major role in the accurate evaluation of the stellar production of $$^{60}$$Fe.

論文

Anisotropic thermal lattice expansion and crystallographic structure of strontium aluminide within Al-10Sr alloy as measured by in-situ neutron diffraction

Liss, K.-D.*; Harjo, S.; 川崎 卓郎; 相澤 一也; 徐 平光

Journal of Alloys and Compounds, 869, p.159232_1 - 159232_9, 2021/07

AA2020-0822.pdf:1.94MB

 被引用回数:6 パーセンタイル:45.20(Chemistry, Physical)

The aluminium strontium master alloy Al-10Sr has been investigated by in-situ neutron diffraction upon a heating-cooling cycle, revealing composition, crystallographic structure, lattice evolution and linear thermal expansion coefficients. Expansion of the Al matrix between (23.5 ... 26.7)$$times$$10$$^{-6}$$ K$$^{-1}$$ depends on temperature and fits well to the literature values, extrapolating to higher temperature at 800 K. Thermal expansion is highly anisotropic for tetragonal Al$$_{4}$$Sr by a factor of 1.86 with values of 20.8 and 11.1$$times$$10$$^{-6}$$ K$$^{-1}$$ in ${it a}$ and ${it c}$-axis. The even large discrepancy to the Al matrix is prone to residual intergranular phase stresses, explaining the brittleness of such composite material. Upon first heating, recovery of the initially plastically deformed materials is observed until 600 K and 700 K, for Al$$_{4}$$Sr and Al. Rietveld analysis refines the 4${it e}$ Wyckoff positions of the ${it I}$ 4/${it m m m}$ crystal structure to ${it z}$ = 0.39 revealing that local tetrahedrons are regular while local hexagons are stretched, in contrast to the literature. Its lattice parameters report to $$a_{rm I}$$ = 4.44240(48) ${AA}$, $$c_{rm I}$$ = 11.0836(15) ${AA}$ at 300 K. Furthermore, the manuscript demonstrates full technical analysis of the neutron data. Findings feed into data bases and an outlook for improving mechanical properties of Al$$_{4}$$Sr composites is given.

論文

Field-tuned magnetic structure and phase diagram of the honeycomb magnet YbCl$$_3$$

Hao, Y. Q.*; Wo, H. L.*; Gu, Y. M.*; Zhang, X. W.*; Gu, Y. Q.*; Zheng, S. Y.*; Zhao, Y.*; Xu, G. Y.*; Lynn, J. W.*; 中島 健次; et al.

Science China; Physics, Mechanics & Astronomy, 64(3), p.237411_1 - 237411_6, 2021/03

 被引用回数:6 パーセンタイル:59.12(Physics, Multidisciplinary)

We report thermodynamic and neutron diffraction measurements on the magnetic ordering properties of the honeycomb lattice magnet YbCl$$_3$$. We find YbCl$$_3$$ exhibits a N${'e}$el type long-range magnetic order at the wavevector (0, 0, 0) below T$$_N$$ = 600 mK. This magnetic order is associated with a small sharp peak in heat capacity and most magnetic entropy release occurs above the magnetic ordering temperature. The magnetic moment lies in-plane, parallel to the monoclinic a-axis, whose magnitude m$$_{rm Yb}$$ = 0.86(3) $$mu_B$$ is considerably smaller than the expected fully ordered moment of 2.24 $$mu_B$$ for the doublet crystal-field ground state. The magnetic ordering moment gradually increases with increasing magnetic field perpendicular to the ab-plane, reaching a maximum value of 1.6(2) $$mu_B$$ at 4 T, before it is completely suppressed above $$sim$$9 T. These results indicate the presence of strong quantum fluctuations in YbCl$$_3$$.

論文

Quasifree neutron knockout reaction reveals a small $$s$$-Orbital component in the Borromean nucleus $$^{17}$$B

Yang, Z. H.*; 久保田 悠樹*; Corsi, A.*; 吉田 数貴; Sun, X.-X.*; Li, J. G.*; 木村 真明*; Michel, N.*; 緒方 一介*; Yuan, C. X.*; et al.

Physical Review Letters, 126(8), p.082501_1 - 082501_8, 2021/02

AA2020-0819.pdf:1.29MB

 被引用回数:45 パーセンタイル:96.73(Physics, Multidisciplinary)

ボロミアン核であり中性子ハロー構造が期待される$$^{17}$$Bに対する($$p$$,$$pn$$)反応実験を行った。断面積の運動量分布を分析することで、$$1s_{1/2}$$$$0d_{5/2}$$軌道の分光学的因子を決定した。驚くべきことに、$$1s_{1/2}$$の分光学的因子は9(2)%と小さいことが明らかになった。この結果は、連続状態を含むdeformed relativistic Hartree-Bogoliubov理論によってよく説明された。本研究の結果によると、現在知られているハロー構造を持つとされる原子核の中で$$^{17}$$Bは$$s$$および$$p$$軌道の成分が最も小さく、$$s$$または$$p$$軌道成分が支配的であることが必ずしもハロー構造の前提条件ではない可能性を示唆している。

論文

Shell structure of the neutron-rich isotopes $$^{69,71,73}$$Co

Lokotko, T.*; Leblond, S.*; Lee, J.*; Doornenbal, P.*; Obertelli, A.*; Poves, A.*; Nowacki, F.*; 緒方 一介*; 吉田 数貴; Authelet, G.*; et al.

Physical Review C, 101(3), p.034314_1 - 034314_7, 2020/03

 被引用回数:10 パーセンタイル:75.41(Physics, Nuclear)

中性子過剰核である$$^{69,71,73}$$Coに対する($$p,2p$$)ノックアウト反応が理化学研究所RIBFで測定された。$$gamma-gamma$$ coincidenceの方法で準位構造が決定され、測定された包括的断面積および排他的断面積から暫定的ではあるがスピン・パリティが決定された。殻模型計算との比較により、$$^{69,71,73}$$Coの低励起状態には球形核と変形核が共存することが示唆された。

論文

Microstructural features and ductile-brittle transition behavior in hot-rolled lean duplex stainless steels

高橋 治*; 渋井 洋平*; 徐 平光; Harjo, S.; 鈴木 徹也*; 友田 陽*

Quantum Beam Science (Internet), 4(1), p.16_1 - 16_15, 2020/03

The characteristics of texture and microstructure of lean duplex stainless steels with low Ni content produced through hot rolling followed by annealing were investigated locally with electron backscatter diffraction and globally with neutron diffraction. Then, the ductile-brittle transition (DBT) behavior was studied by Charpy impact test. It is found that the DBT temperature (DBTT) is strongly affected by the direction of crack propagation, depending on crystallographic texture and microstructural morphology; the DBTT becomes extremely low in the case of fracture accompanying delamination. A high Ni duplex stainless steel examined for comparison, shows a lower DBTT compared with the lean steel in the same crack propagating direction. The obtained results were also discussed through comparing with those of cast duplex stainless steels reported previously (Takahashi et al., Tetsu-to-Hagane, 100(2014), 1150).

論文

IAEA Photonuclear Data Library 2019

河野 俊彦*; Cho, Y. S.*; Dimitriou, P.*; Filipescu, D.*; 岩本 信之; Plujko, V.*; Tao, X.*; 宇都宮 弘章*; Varlamov, V.*; Xu, R.*; et al.

Nuclear Data Sheets, 163, p.109 - 162, 2020/01

 被引用回数:83 パーセンタイル:99.69(Physics, Nuclear)

We report our coordinated efforts to address these data needs such as radiation shielding design and radiation transport analyses, and present the results of the new evaluations of more than 200 nuclides included in the new updated IAEA Photonuclear Data Library, where the photon energy goes up to 200 MeV. We discuss the new assessment method and make recommendations to the user community in cases where the experimental data are discrepant and the assessments disagree. In addition, in the absence of experimental data, we present model predictions for photon-induced reaction cross section on nuclides of potential interest to medical radioisotope production.

論文

Fine structure in the $$alpha$$ decay of $$^{223}$$U

Sun, M. D.*; Liu, Z.*; Huang, T. H.*; Zhang, W. Q.*; Andreyev, A. N.; Ding, B.*; Wang, J. G.*; Liu, X. Y.*; Lu, H. Y.*; Hou, D. S.*; et al.

Physics Letters B, 800, p.135096_1 - 135096_5, 2020/01

 被引用回数:11 パーセンタイル:78.07(Astronomy & Astrophysics)

Fine structure in the $$alpha$$ decay of $$^{223}$$U was observed in the fusion-evaporation reaction $$^{187}$$Re($$^{40}$$Ar,p3n) by using fast digital pulse processing technique. Two $$alpha$$-decay branches of $$^{223}$$U feeding the ground state and 244 keV excited state of $$^{219}$$Th were identified by establishing the decay chain $$^{223}$$U$$rightarrow$$$$^{219}$$Th$$rightarrow$$$$^{215}$$Ra$$rightarrow$$$$^{211}$$Rn. The $$alpha$$-particle energy for the ground-state to ground-state transition of $$^{223}$$U was determined to be 8993(17) keV, 213 keV higher than the previous value, the half-life was updated to be 62$$^{+14}_{-10} mu$$s. Evolution of nuclear structure for $$N$$=131 even-$$Z$$ isotones from Po to U was discussed in the frameworks of nuclear mass and reduced $$alpha$$-decay width, a weakening octupole deformation in the ground state of $$^{223}$$U relative to its lighter isotones $$^{219}$$Ra and $$^{211}$$Th was suggested.

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